As part of an effort to develop drought-resistant food and bioenergy crops, scientists at the Department of Energy's Oak Ridge National Laboratory have uncovered the genetic and metabolic mechanisms that allow certain plants ...

Venus is often called Earth's "Sister Planet" because of all the things they have in common. They are comparable in size, have similar compositions, and both orbit within the Sun's habitable zone. But beyond that, there are ...

Dramatic climate cycles on early Mars, triggered by buildup of greenhouse gases, may be the key to understanding how liquid water left its mark on the planet's surface, according to a team of planetary scientists.

Ecological processes govern seasonal changes in microbial communities living along rivers in the hyporheic zone, where groundwater and surface water mix. These processes have been well-studied in plant and animal communities. ...

Whether intentionally set to consume agricultural waste or naturally ignited in forests or peatlands, open-burning fires impact the global climate system in two ways which, to some extent, cancel each other out. On one hand, ...

(Phys.org)—A pair of researchers with the University of Alberta in Canada has found that shedding and production of new tissue in sponges is much more complicated and slower than has been thought. In their paper published ...

Australian researchers have discovered that the common Panic grasses could hold the secret to increasing the yields of cereal crops and help feed the world with increasing temperature extremes and a population of nearly 10 ...

Carbon and nitrogen are central to life on Earth – life cannot exist without them, but an overabundance in the atmosphere imperils the life we have. So how much carbon and nitrogen is there on (and in) planet Earth? And ...

An international team has discovered a genetic mechanism that is responsible for the development of stomata - microscopic valves on the surface of plants that facilitate the uptake of carbon dioxide and the release of oxygen ...

Carbon dioxide

Carbon dioxide (chemical formula: CO2) is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. It is a gas at standard temperature and pressure and exists in Earth's atmosphere in this state.

Carbon dioxide is used by plants during photosynthesis to make sugars, which may either be consumed in respiration or used as the raw material to produce other organic compounds needed for plant growth and development. It is produced during respiration by plants, and by all animals, fungi and microorganisms that depend either directly or indirectly on plants for food. It is thus a major component of the carbon cycle. Carbon dioxide is generated as a by-product of the combustion of fossil fuels or the burning of vegetable matter, among other chemical processes. Large amounts of carbon dioxide are emitted from volcanoes and other geothermal processes such as hot springs and geysers and by the dissolution of carbonates in crustal rocks.

As of March 2009[update], carbon dioxide in the Earth's atmosphere is at a concentration of 387 ppm by volume. Atmospheric concentrations of carbon dioxide fluctuate slightly with the change of the seasons, driven primarily by seasonal plant growth in the Northern Hemisphere. Concentrations of carbon dioxide fall during the northern spring and summer as plants consume the gas, and rise during the northern autumn and winter as plants go dormant, die and decay. Carbon dioxide is a greenhouse gas as it transmits visible light but absorbs strongly in the infrared and near-infrared.

Carbon dioxide has no liquid state at pressures below 5.1 atmospheres. At 1 atmosphere (near mean sea level pressure), the gas deposits directly to a solid at temperatures below −78 °C and the solid sublimes directly to a gas above −78 °C. In its solid state, carbon dioxide is commonly called dry ice.

CO2 is an acidic oxide: an aqueous solution turns litmus from blue to pink. It is the anhydride of carbonic acid, an acid which is unstable and is known to exist only in aqueous solution.

CO2 is toxic in higher concentrations: 1% (10,000 ppm) will make some people feel drowsy. Concentrations of 7% to 10% cause dizziness, headache, visual and hearing dysfunction, and unconsciousness within a few minutes to an hour.